FreeBSD-5.3/usr.bin/m4/expr.c
/* $OpenBSD: expr.c,v 1.14 2002/04/26 16:15:16 espie Exp $ */
/* $NetBSD: expr.c,v 1.7 1995/09/28 05:37:31 tls Exp $ */
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Ozan Yigit at York University.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)expr.c 8.2 (Berkeley) 4/29/95";
#else
#if 0
static char rcsid[] = "$OpenBSD: expr.c,v 1.14 2002/04/26 16:15:16 espie Exp $";
#endif
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/usr.bin/m4/expr.c,v 1.14 2004/05/01 03:59:43 smkelly Exp $");
#include <sys/types.h>
#include <ctype.h>
#include <err.h>
#include <stddef.h>
#include <stdio.h>
#include "mdef.h"
#include "extern.h"
/*
* expression evaluator: performs a standard recursive
* descent parse to evaluate any expression permissible
* within the following grammar:
*
* expr : query EOS
* query : lor
* | lor "?" query ":" query
* lor : land { "||" land }
* land : bor { "&&" bor }
* bor : xor { "|" xor }
* xor : band { "^" eqrel }
* band : eqrel { "&" eqrel }
* eqrel : nerel { ("==" | "!=") nerel }
* nerel : shift { ("<" | ">" | "<=" | ">=") shift }
* shift : primary { ("<<" | ">>") primary }
* primary : term { ("+" | "-") term }
* term : exp { ("*" | "/" | "%") exp }
* exp : unary { "**" unary }
* unary : factor
* | ("+" | "-" | "~" | "!") unary
* factor : constant
* | "(" query ")"
* constant: num
* | "'" CHAR "'"
* num : DIGIT
* | DIGIT num
*
*
* This expression evaluator is lifted from a public-domain
* C Pre-Processor included with the DECUS C Compiler distribution.
* It is hacked somewhat to be suitable for m4.
*
* Originally by: Mike Lutz
* Bob Harper
*/
#define EQL 0
#define NEQ 1
#define LSS 2
#define LEQ 3
#define GTR 4
#define GEQ 5
#define OCTAL 8
#define DECIMAL 10
#define HEX 16
static const char *nxtch; /* Parser scan pointer */
static const char *where;
static int query(int mayeval);
static int lor(int mayeval);
static int land(int mayeval);
static int bor(int mayeval);
static int xor(int mayeval);
static int band(int mayeval);
static int eqrel(int mayeval);
static int nerel(int mayeval);
static int shift(int mayeval);
static int primary(int mayeval);
static int term(int mayeval);
static int exp(int mayeval);
static int unary(int mayeval);
static int factor(int mayeval);
static int constant(int mayeval);
static int num(int mayeval);
static int geteqrel(int mayeval);
static int skipws(void);
static void experr(const char *);
/*
* For longjmp
*/
#include <setjmp.h>
static jmp_buf expjump;
/*
* macros:
* ungetch - Put back the last character examined.
* getch - return the next character from expr string.
*/
#define ungetch() nxtch--
#define getch() *nxtch++
int
expr(const char *expbuf)
{
int rval;
nxtch = expbuf;
where = expbuf;
if (setjmp(expjump) != 0)
return FALSE;
rval = query(1);
if (skipws() == EOS)
return rval;
printf("m4: ill-formed expression.\n");
return FALSE;
}
/*
* query : lor | lor '?' query ':' query
*/
static int
query(int mayeval)
{
int result, true_val, false_val;
result = lor(mayeval);
if (skipws() != '?') {
ungetch();
return result;
}
true_val = query(result);
if (skipws() != ':')
experr("bad query: missing \":\"");
false_val = query(!result);
return result ? true_val : false_val;
}
/*
* lor : land { '||' land }
*/
static int
lor(int mayeval)
{
int c, vl, vr;
vl = land(mayeval);
while ((c = skipws()) == '|') {
if (getch() != '|') {
ungetch();
break;
}
if (vl != 0)
mayeval = 0;
vr = land(mayeval);
vl = vl || vr;
}
ungetch();
return vl;
}
/*
* land : not { '&&' not }
*/
static int
land(int mayeval)
{
int c, vl, vr;
vl = bor(mayeval);
while ((c = skipws()) == '&') {
if (getch() != '&') {
ungetch();
break;
}
if (vl == 0)
mayeval = 0;
vr = bor(mayeval);
vl = vl && vr;
}
ungetch();
return vl;
}
/*
* bor : xor { "|" xor }
*/
static int
bor(int mayeval)
{
int vl, vr, c, cr;
vl = xor(mayeval);
while ((c = skipws()) == '|') {
cr = getch();
ungetch();
if (cr == '|')
break;
vr = xor(mayeval);
vl |= vr;
}
ungetch();
return (vl);
}
/*
* xor : band { "^" band }
*/
static int
xor(int mayeval)
{
int vl, vr, c;
vl = band(mayeval);
while ((c = skipws()) == '^') {
vr = band(mayeval);
vl ^= vr;
}
ungetch();
return (vl);
}
/*
* band : eqrel { "&" eqrel }
*/
static int
band(int mayeval)
{
int c, cr, vl, vr;
vl = eqrel(mayeval);
while ((c = skipws()) == '&') {
cr = getch();
ungetch();
if (cr == '&')
break;
vr = eqrel(mayeval);
vl &= vr;
}
ungetch();
return vl;
}
/*
* eqrel : nerel { ("==" | "!=" ) nerel }
*/
static int
eqrel(int mayeval)
{
int vl, vr, c, cr;
vl = nerel(mayeval);
while ((c = skipws()) == '!' || c == '=') {
if ((cr = getch()) != '=') {
ungetch();
break;
}
vr = nerel(mayeval);
switch (c) {
case '=':
vl = (vl == vr);
break;
case '!':
vl = (vl != vr);
break;
}
}
ungetch();
return vl;
}
/*
* nerel : shift { ("<=" | ">=" | "<" | ">") shift }
*/
static int
nerel(int mayeval)
{
int vl, vr, c, cr;
vl = shift(mayeval);
while ((c = skipws()) == '<' || c == '>') {
if ((cr = getch()) != '=') {
ungetch();
cr = '\0';
}
vr = shift(mayeval);
switch (c) {
case '<':
vl = (cr == '\0') ? (vl < vr) : (vl <= vr);
break;
case '>':
vl = (cr == '\0') ? (vl > vr) : (vl >= vr);
break;
}
}
ungetch();
return vl;
}
/*
* shift : primary { ("<<" | ">>") primary }
*/
static int
shift(int mayeval)
{
int vl, vr, c;
vl = primary(mayeval);
while (((c = skipws()) == '<' || c == '>') && getch() == c) {
vr = primary(mayeval);
if (c == '<')
vl <<= vr;
else
vl >>= vr;
}
if (c == '<' || c == '>')
ungetch();
ungetch();
return vl;
}
/*
* primary : term { ("+" | "-") term }
*/
static int
primary(int mayeval)
{
int c, vl, vr;
vl = term(mayeval);
while ((c = skipws()) == '+' || c == '-') {
vr = term(mayeval);
if (c == '+')
vl += vr;
else
vl -= vr;
}
ungetch();
return vl;
}
/*
* term : exp { ("*" | "/" | "%") exp }
*/
static int
term(int mayeval)
{
int c, vl, vr;
vl = exp(mayeval);
while ((c = skipws()) == '*' || c == '/' || c == '%') {
vr = exp(mayeval);
switch (c) {
case '*':
vl *= vr;
break;
case '/':
if (!mayeval)
/* short-circuit */;
else if (vr == 0)
errx(1, "division by zero in eval.");
else
vl /= vr;
break;
case '%':
if (!mayeval)
/* short-circuit */;
else if (vr == 0)
errx(1, "modulo zero in eval.");
else
vl %= vr;
break;
}
}
ungetch();
return vl;
}
/*
* exp : unary { "**" exp }
*/
static int
exp(int mayeval)
{
int c, vl, vr, n;
vl = unary(mayeval);
while ((c = skipws()) == '*') {
if (getch() != '*') {
ungetch();
break;
}
vr = unary(mayeval);
n = 1;
while (vr-- > 0)
n *= vl;
return n;
}
ungetch();
return vl;
}
/*
* unary : factor | ("+" | "-" | "~" | "!") unary
*/
static int
unary(int mayeval)
{
int val, c;
if ((c = skipws()) == '+' || c == '-' || c == '~' || c == '!') {
val = unary(mayeval);
switch (c) {
case '+':
return val;
case '-':
return -val;
case '~':
return ~val;
case '!':
return !val;
}
}
ungetch();
return factor(mayeval);
}
/*
* factor : constant | '(' query ')'
*/
static int
factor(int mayeval)
{
int val;
if (skipws() == '(') {
val = query(mayeval);
if (skipws() != ')')
experr("bad factor: missing \")\"");
return val;
}
ungetch();
return constant(mayeval);
}
/*
* constant: num | 'char'
* Note: constant() handles multi-byte constants
*/
static int
constant(int mayeval)
{
int i;
int value;
int c;
int v[sizeof(int)];
if (skipws() != '\'') {
ungetch();
return num(mayeval);
}
for (i = 0; i < (ssize_t)sizeof(int); i++) {
if ((c = getch()) == '\'') {
ungetch();
break;
}
if (c == '\\') {
switch (c = getch()) {
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
ungetch();
c = num(mayeval);
break;
case 'n':
c = 012;
break;
case 'r':
c = 015;
break;
case 't':
c = 011;
break;
case 'b':
c = 010;
break;
case 'f':
c = 014;
break;
}
}
v[i] = c;
}
if (i == 0 || getch() != '\'')
experr("illegal character constant");
for (value = 0; --i >= 0;) {
value <<= 8;
value += v[i];
}
return value;
}
/*
* num : digit | num digit
*/
static int
num(int mayeval)
{
int rval, c, base;
int ndig;
rval = 0;
ndig = 0;
c = skipws();
if (c == '0') {
c = skipws();
if (c == 'x' || c == 'X') {
base = HEX;
c = skipws();
} else {
base = OCTAL;
ndig++;
}
} else
base = DECIMAL;
for(;;) {
switch(c) {
case '8': case '9':
if (base == OCTAL)
goto bad_digit;
/*FALLTHRU*/
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
rval *= base;
rval += c - '0';
break;
case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
c = tolower(c);
case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
if (base == HEX) {
rval *= base;
rval += c - 'a' + 10;
break;
}
/*FALLTHRU*/
default:
goto bad_digit;
}
c = getch();
ndig++;
}
bad_digit:
ungetch();
if (ndig == 0)
experr("bad constant");
return rval;
}
/*
* Skip over any white space and return terminating char.
*/
static int
skipws(void)
{
int c;
while ((c = getch()) <= ' ' && c > EOS)
;
return c;
}
/*
* resets environment to eval(), prints an error
* and forces eval to return FALSE.
*/
static void
experr(const char *msg)
{
printf("m4: %s in expr %s.\n", msg, where);
longjmp(expjump, -1);
}